This invention relates to a process and system for forming a total containment and sterile connection between two tubes.
At the present time, there are a number of medical and scientific procedures that require sterile transfer of dangerous or sensitive fluids from one container to another. This protects the internal fluids from external contamination. The fluids themselves, however, are frequently biologically or chemically dangerous. This is particularly true for medical personnel handling body fluids where AIDS, hepatitus or chemo-therapy agents are present. Total containment of the fluids therefore is important to protect patients and medical personnel from the dangers of infection from contact with the fluids.
An example of the need for a total containment, sterile system is in whole blood processing. Although great care is exercised to collect blood that is biologically clean, the organisms associated with AIDS and hepatitus are difficult to screen. Moreover, scientific work on the AIDS and hepatitus viruses require that the organism be present in the fluid samples. In either event the medical and scientific investigators are at high risk.
High risk areas associated with most body fluid handling are:
(a) Blood processing PA0 (b) Bio-Medical technology Labs PA0 (c) Dialysis, hemo and CAPD PA0 (d) Total Parenteral feeding PA0 (e) Chemo-therapy PA0 (f) Urinary drainage (Post Operative) PA0 (g) Indwelling catheters
There is also a need for sterile connections for blood bags. At present, blood from a donor is drawn into a primary bag which may be joined to one or two satellite bags, all connected and sterilized before use. These satellite bags may be needed for holding blood separated components, such as plasma or platelets; treating agents, such as bases, buffers; stabilizers for cell metabolism, other preservatives, or rejuvenants; or washes to remove a treating agent or other contaminant. Actually, it is not feasible to have preconnected bags for all the treatments which may be desired. Supplemental treatment such as fresh preservative cannot now be added sterily during bag storage by any commercially acceptable procedure. In addition, to avoid the expense of unused satellite bags, the number of such bags is chosen based on limited, predicted needs. The inability to forecast needs well adds greatly to inventory requirements and complicates scheduling of blood donations.
Currently, very limited use is made of quality control as a time assay of the quantity and quality of components in separated blood fractions. The main reason for the current limited use is that heretofore any entry into a sterile blood unit exposed the blood to bacteria, thereby requiring that the blood be used within 24 hours from entry. Hence, although the viability of stored blood components can be extended by supplemental treatments, such treatments are usually not effective.
Moreover, the primary blood bag contains anticoagulant which can be sterilized only by heat (steam); thus all preconnected bags are also sterilized by wet-sterilization techniques, i.e., steam or hot water in an autoclave apparatus. These bags are also made of plasticized polyvinyl chloride (PVC), although other materials are known to be useful for constructing bags which are favorable for other reasons, such as greater oxygen permeability. Since many such materials, e.g., oxygen permeable polyethylene, are not steam sterilizable, they are not used in preconnected systems.
A sterile docking means would permit one to effect whatever processing is desired without compromising sterility, limiting storage life or requiring the preconnection of a multitude of bags, all wet-sterilizable, without knowing which, if any will be used.
In urinary drainage for example, it is important to ensure that no external organisms enter the system. The implanted catheter by-passes the body's immune defenses. Entry of bacteria into the system therefore can lead to bladder infections and possible life threatening bacteremia. The sterile connection feature of this invention safeguards this eventuality.
Hospital nurses also are at risk. The full bag of urine is exchanged by the nurse for an empty one. The full bag contents are weighed, and the urine disposed of. In this situation, it is extremely difficult to prevent urine from contacting the nurse's hands. A slight cut or opening contacted by AIDS or hepatitus organisms can lead to infection. The total containment features of this invention prevents this type of mishap.
Continuous ambulatory peritoneal dialysis (CAPD), is a procedure which replaces hemo-dialysis (a method of using membrane diffusion to wash the blood outside the body). The CAPD patient has a tube connected to his or her peritoneal cavity via an implanted catheter. A tube from a bag of fresh dialysis solution is connected to the patient's tube. The fresh dialysis solution is drained from the bag into the patient's peritoneal cavity where it remains for about 3-4 hours. During this treatment period, the empty bag is folded and carried by the patient who can continue with his or her normal activities. After this treatment period, the spent dialysate is drained back into the empty bag which is then disconnected from the patient's tube. A bag of fresh dialysis solution is then connected to the patient's tube and the procedure is repeated. Connection to a new bag of dialysis solution exposed the tube ends to airborne bacteria or other contamination even though precautions are taken. No satisfactory way heretofore has existed to insure sterility in spite of the elaborate and costly precautions now employed including the use of masks, gloves, gauze strips and disinfectant solutions. Usually, contamination does occur to the extent that a case of peritonitis is contracted perhaps on the average once or more a year and scar tissue from it inhibits dialysis.
Truly sterile connections could minimize the occurrence of peritonitis. Also any other treatment bags, such as for an antibiotic, bacteriostat, or other medications, could be connected as desired. The total containment capability of this patent provides for two further important features for CAPD.
The spent CAPD solution is totally contained in the spent bag and tube. This prevents accidental spillage or seepage of a fluid that could be biologically dangerous. Even if the patient accidentally reverses the tubes, he or she is still protected by the system remaining closed. The patient, recognizing the error, need only reload the same tubes and proceed to making the correct transfer.
A second advantage of the totally closed system is the ability to "bag-off". This is a situation where the patient does not wish to roll up the bag and tubing and wear it until the next exchange. While the dialysis solution is in the peritoneum the bag can be removed, thus the patients are free of a cumbersome and uncomfortable bulk under their clothing. The patient's life style is closer to normal. "Bagging-on" can also be a sterile-totally contained procedure.
U.S. Pat. Nos. 4,369,779 and 4,610,670 are generally directed to practices for such butt welding of plastic tubes. The various practices heretofore generally involve placing the two tubes to be welded in grooves in side by side holders. The holders move toward the heated wafer which in turn cuts through the tubes while also heating the tubes to their welding temperature. U.S. Pat. No. 4,619,642 discloses a variation of these practices wherein a cold cutting tool is used. A critical step in these practices involves the realignment of the tubes after the cutting process. This is accomplished by moving one of the holders with its cut tubes forwardly of the other holder so that a different pair of tube segments becomes aligned. The holders are then relatively moved toward each other to cause the realigned set of tubes to contact each other and become butt welded together. The result of this process is a pair of tube sections connected together and a second pair of tube sections unconnected to each other. The process has a number of disadvantages relating to the controls and consequently added expenditure resulting from the more complicated arrangement needed for the realigning step.